When oxidized, a dull grayish film forms on the surface of aluminum, which spoils its beautiful finish. Natural solutions, including lemon and vinegar, tend to oxidize aluminum easily. But be careful with abrasive cleaners as they can scratch the aluminum. Painted aluminum can be more serious, such as chemical abrasion corrosion (especially in boats).
Steps
Method 1 of 3: How to clean aluminum oxide on cookware

Step 1. Remove dust and dirt with a soft bristled brush
Before proceeding with the elimination of traces of corrosion, it is necessary to clean it of dust or dirt. Use a non-abrasive cleaner such as dishwashing detergent.

Step 2. Boil the burnt food
To clean burnt food from the bottom of the pot without damaging it, fill the pot with 5 centimeters of water. Put it on fire, bring water to a boil and simmer for another 10 minutes. Remove the pot from the stove and scoop out the sour food with a wooden kitchen spatula. Repeat until the pot is clean.
Be careful not to use steel wool to remove burnt food, as this can scratch the pot and make it difficult to clean

Step 3. Boil vinegar or lemon juice in a saucepan
To eliminate oxidation, mix water with vinegar or lemon juice in a saucepan. Put the saucepan on the fire, bring the solution to a boil and boil it for fifteen minutes. If you have other small aluminum cookware that needs to be processed, put that in the pot as well.
For 1 liter of water in the solution, there should be at least 2 tablespoons (30 ml) of lemon juice or vinegar

Step 4. Rinse thoroughly and dry the pan
Rinse the dishes under warm water to remove any leftover lemon juice or vinegar, then dry them with a cloth.
Method 2 of 3: How to remove alumina from large surfaces

Step 1. Wipe the surface with a soft bristled brush to remove any dirt
Try to brush off all dust and coarse particles.

Step 2. Wipe it with detergent and a sponge
Dampen a sponge with water and apply detergent to it. Do not wipe the surface too hard. This may be enough to remove oxidation.

Step 3. Use lemon
If the detergent doesn't handle oxidation, use lemon. Cut lemon in half and sprinkle salt on top. Wipe the surface of the aluminum with the inside of the lemon so that the salt and citric acid remove the alumina. Since salt is abrasive, rub gently.
Apply lemon juice and salt to a rag to gently wipe down the aluminum

Step 4. For severe oxidation, use an aluminum blackener
To remove oxidation, take aluminum blackening cleaner and apply it to a 0000 or 000 grit stainless steel wire wool. Wear gloves and apply the cleaner to problem areas. Rub as gently as possible to remove any traces of corrosion.

Step 5. Wipe the aluminum with a clean sponge
Do not allow cleaner, lemon or other cleaning agents to dry on the aluminum surface. Wipe the aluminum thoroughly with a clean, damp sponge.
Method 3 of 3: How to Prevent Chemical Abrasion Corrosion

Step 1. Look out for cracks in the paint
Despite all its ugliness, the paint prevents aluminum oxidation and abrasive chemical corrosion. When paint starts to crack on aluminum surfaces, which are often in contact with water, the aluminum begins to break down with abrasive chemical corrosion.
Externally, abrasive chemical corrosion appears as a white powder or white slime

Step 2. Remove pieces of paint
Scrape off the paint from where it starts to crack. Use a putty knife to pick up and remove the paint.
Use 220 grit sandpaper to remove paint from larger surfaces. Gradually blend along the edges between the painted surface and the metal

Step 3. Use a generic paint thinner to clean the surface
Apply solvent to a rag. Use a rag to wipe down the area where you scraped off the paint.

Step 4. Apply epoxy paint
Choose a matching epoxy paint. Apply a couple of coats of paint with a brush. It is not necessary to apply a primer before painting a small spot.

Step 5. Apply sealant to the edges of metal products
Moving parts such as fasteners and clamps loosen surrounding paint as they move. Therefore, new paint in such places will not last long. Instead, apply a low adhesion polyurethane or polysulfide sealant to the edges of the part. Fix the entire circumference of the part so that not a drop of paint seeps into the aluminum.